The general notion of pre-Columbian Native Americans is that all of them were hunter-gatherers like the archetypal bison hunters of the Great Plains. Yet by the time Columbus arrived in the New World, hunter-gatherers were as rare in North America as they were in, say, Eastern Europe at the same time. By and large, Native Americans of 1492 were farmers, settled agricultural people, but there were, at the same time, pockets of hunter-gatherers across the landscape. Paleoanthropologists have examined skeletal remains of both groups in detail and found general agreement with the record worldwide and through time. The hunter-gatherers were taller, less deformed, showed no evidence of diseases of civilization like dental cavities and no deformation of their bodies; but the skeletons of the contemporaneous Native American farmers revealed all of these problems. Native Americans showed evidence of suffering diseases of civilization long before Western civilization arrived, which is why we need to define civilization as the arrival of domestication, of agriculture. We are really talking about diseases of agriculture and adoption of the sedentary way of life.
Now we have arrived at the point in this argument that, according to established ritual, requires an insertion of a disclaimer, the “yeah, but…” These discussions generally become defensive, as if anyone raising these ideas is attacking the very core of civilization and advocating a return to living in caves. It is true enough that despite the costs, civilization came with considerable benefits: our kids don’t die as often now, and we need not fear infection (as much) or a full load of body parasites. The disclaimer is indeed warranted but nonetheless misses the point. The costs associated with civilization, the diseases of civilization, are to some degree reversible. By paying close attention to what lies at the root of this series of problems, we can erase some of these costs. We can learn from our ancestors to steer our way to well-being. And it turns out that while these issues in all their layers are as complex as civilization itself, the root, the one central development that gets us to maybe 80 percent of what ails us, is simple: it is glucose and glucose alone, in all its permutations. In the end, this discussion will gather threads as diverse as violence, infant attachment, tribalism, meditation, and dance, but we must begin with glucose, because that’s where civilization began.
IT’S THE GLUCOSE
In many ways, it took ten thousand years of gradual change to mold us in the shape we are in today. We like to fault modern industrial agriculture and everything that goes with it—overpopulation, a hyperindustrialized food chain, and sedentary living—as underlying the epidemic sweep of diseases of civilization. But the fact is, these all began millennia ago, when humans first domesticated grain. This is a bedrock belief among anthropologists. The effects of the Industrial Revolution and the Information Age pale in comparison with the effects of the advent of agriculture, the single greatest change in two million years of hominid history. So profound were its effects on humanity that it has been said it makes every bit as much sense to argue that wheat domesticated us as the more usual and opposite statement.
Yet it’s wrong to say that humanity has been living under agriculture for ten thousand years and that it all traces to wheat. Wheat was simply the Western side of the story. True enough, agriculture did begin with the domestication of wheat about ten millennia ago, but early farming was far more integrated with hunting and gathering for several thousand years and did not do much to reorganize the human endeavor until maybe six thousand years ago in the areas that are now Iraq and Turkey. Further, agriculture also began with independent domestication of separate crops in a continuous process stretching to maybe five thousand years ago, with the domestication of rice in Asia and Africa, maize in Central America, and tubers like potatoes in South America. All spawned separate civilizations, but crucially, except for the South American case of potatoes, all were based in the taming and cultivation of a wild grass (yes, rice, wheat, and corn, or maize, as most of the world knows it, are grasses), and all, including the tubers, rested on plants that stored dense, durable packages of carbohydrates: starches. This is civilization. Civilization is starch, and by extension, diseases of civilization are diseases of starch, either directly or indirectly, and most of it is indeed direct: starches are complex carbohydrates, and they quickly break down, often even in a person’s mouth, into simple carbohydrates, which are sugars. Further, much of that sugar is glucose or other forms that the liver converts into glucose.
The human body is perfectly capable of metabolizing glucose, which has been with us through the ages, especially in fruits and tubers. We convert it into glycogen, and any athlete will tell you that glycogen is what moves us forward. (It turns out that this is not nearly as true as we think, but for the moment, let’s let this stand.) It is not that glucose is unprecedented or even that starch is new to us; hunter-gatherers have and had both. But not in abundance, not as a sole source, not in the tidal wave of starches that agriculture would begin yielding ten thousand years ago, a wave that has built exponentially in our time.
Today, those three wild grasses—rice, wheat, and corn—are the three most dominant forms of human nutrition, and the potatoes domesticated in South America are the fourth. About 75 percent of all human nutrition derives from those four sources alone. To oversimplify just a bit, this is what ails us, and we will unpack this idea in the next chapter, where we’ll look at the diseases of civilization clustered around metabolic syndrome, the most important and most devastating of these ailments. Reversing this is where we can begin reversing the worst effects of the way we live. In effect, this is the reversal of domestication, which is to say the first step in going wild. Still, this issue does not end with glucose, obesity, and type 2 diabetes.
Dense packages of storable starch allowed sedentary lives. That is, we no longer needed to range far and wide as nomadic hunter-gatherer societies had done for a couple of million years; we could spend our lives in a single location—or, as this tendency has played out in modern times, in a single chair. Domestication allowed cities. Domestication created new sources of protein but also new sources of disease, because most of our infectious diseases come from domesticated animals, especially chickens and swine. Storage of grain, though, also allowed accumulation of wealth, almost immediately accruing preferentially to a few individuals. Evidence of disparate wealth is abundantly clear in the archaeological record in the very first agricultural cities, yet it’s unknown in hunter-gatherer societies, both in the archaeological record and among contemporary wild people. By allowing wealth, civilization, by extension, created poverty.
Grain allows soft food for infants, and a sedentary life allows women to begin producing children earlier and more often, which is to say that grain greatly accelerated population growth.
These are the most cited and most obvious effects of domestication. The more subtle implications are just as interesting. For instance, remember that we began by talking about cancer, which develops from a complex set of circumstances through lifetimes. The story of cancer and civilization yields to no simple telling, but a quick look at one small example is illustrative and important in its own right, especially to women: the epidemic rates of breast and ovarian cancer in our time. But how does this relate to evolution and agriculture?
Evolution is profoundly attentive to a couple of issues: food and reproduction—how we survive day to day and through generations. Nothing is more important to evolution as a trait that speaks to both food and reproduction.
The human body has a long list of mechanisms for assessing well-being, and nowhere are these more important than in reproduction. Science has clearly demonstrated that the body’s sensory systems have highly developed ways of ensuring that babies are born during times of plenty, during times of maximum well-being. The normal time of onset of a first menstrual period for a hunter-gatherer girl is about seventeen years old, which is somewhat surprising for anyone following the corresponding number among modern girls in postindustrial societies. Menarche for this latter group is more like twelve years ol
d.
There is plenty of speculation as to why this is true. Genetic differences? Nope. There are many studies showing, for instance, that when Bangladeshi girls move to England as children, their first periods come at the normal time for English girls, not Bangladeshi girls. Can polluting chemicals and endocrine disruptors or food additives explain this phenomenon? There may well be an effect, but there is a simpler and well-researched explanation: body weight. The fatter a population, the more likely a girl is to menstruate early. Hunter-gatherer girls were and are lean and active and so develop according to nature’s long-term plan. Carbohydrates and sedentary habits in domesticated populations circumvent that plan, simply because such girls are fatter and the body’s sensors rightfully detect flush times. Time to reproduce.
The real downside of this (other than rampant teenage pregnancy, and we hope that you see in our reasoning that we think the coincidence of the epidemic of obesity and teen pregnancy among impoverished girls is more than a coincidence) comes at the end of life, though. Menarche launches girls into a regular cycle of hormones. The result is that any girl who starts early and has a lifetime of menstrual regularity with few pregnancies (lean, athletic girls and women often do not menstruate regularly) has approximately twice as many periods and so twice as many bouts of hormone cycling as hunter-gatherer girls. One of those hormones, progesterone, triggers cell division, and because both breasts and ovaries take strong doses twice as often, those become sites of tumors. This is how both breast and ovarian cancer appear as diseases of civilization. Researchers have examined this and suggested an interesting intervention for both forms of cancer: an exercise program for girls. We agree.
AUTOIMMUNE
The Tsimané people are a surviving population of hunter-gatherers in Brazil’s Amazon rain forest. Doctors studied twelve thousand Tsimané extensively, a total of thirty-seven thousand examinations, and found what, by now, we might expect. No cancer of breast or ovary, but no colon or testicular cancer either. Cardiovascular disease? Absent. No asthma. Zero. One more fault of carbohydrates? Not really. Not directly. Asthma opens a new and fascinating door, and through it we enter a whole new area, a second wave, if you will, of diseases of civilization, one that ought to raise our appreciation of the intricacy of evolution to something approaching awe.
Asthma is an autoimmune disease, and the Tsimané people have about one-fortieth the rate of autoimmune disease as do the people of New York City.
An autoimmune disease is, in simplest terms, an example of the body attacking itself. Something relatively benign, a foreign body but not a real threat, triggers an immune response, and this powerful system suddenly launches the body’s equivalent of all-out thermonuclear war, like a trigger-happy paranoid. This is our new epidemic, what the science writer Moises Velasquez-Manoff aptly labeled “an epidemic of absence.”
First, the problem is indeed epidemic. Run-of-the-mill infectious diseases like rheumatic fever, hepatitis A, tuberculosis, mumps, and measles are all in decline worldwide, declining in some cases from universal in 1950 (everyone then got mumps and measles) to nearly zero today. In that same period, autoimmune diseases like multiple sclerosis, Crohn’s disease, type 1 diabetes, and asthma have at least doubled, in some cases quadrupled.
Second, the epidemic is very new, appearing only in the last generation, and it followed an even more intricate but parallel path to that of diseases of civilization. All the autoimmune diseases showed up first and most markedly in people living at the very pinnacle of civilization, in cities, and in the best areas of cities at that. Penthouse dwellers on the Upper East Side got asthma. Alabama hog farmers did not.
The “absence” part of the characterization, however, is even more interesting. The standard explanation for the prevalence of autoimmune diseases is an idea dating to the 1980s. It suggests that autoimmune diseases are a direct result of our success in eradicating not only bacteria that cause infectious diseases, but also parasites like hookworms.
Velasquez-Manoff summarized the matter: “Immune-mediated disorders arise in direct proportion to affluence and Westernization. The more that one’s surroundings resemble the environment in which we evolved—rife with infections and lots of what one scientist calls ‘animals, faeces and mud’—the lower the prevalence of these diseases.”
This is where the argument gets evolutionary or, more to the point, coevolutionary, a term coined by the conservation biologists Paul Ehrlich and Peter Raven. The hypothesis of coevolution says simply that when species evolve in the presence of each other, in a long-term relationship, removing one can damage the other, even if they are bitter enemies, like wolves and elk or infectious bacteria and humans. It is a rule that says even well-intentioned interventions in natural systems can have profound deleterious consequences. This idea, in fact, is getting some traction among researchers, and today consideration of the human microbiome—the population of microbes that inhabits every human body—is becoming one of the hottest pursuits of medicine. It’s a truly positive development.
The mechanism that produces the epidemic of absence in the case of autoimmune diseases is fairly straightforward, and also evolutionary. Toward the end of the Paleolithic era, as glaciers advanced and pushed a growing human population into a more restricted area, even before farming began, there was an increase in a few infectious diseases like malaria. Over time, evolution adjusted and favored those humans with the most reactive immune systems, and there are specific, known genes for this. The most interesting case study was in Sardinia, an island off of Italy, which was in this period and until modern times plagued by malaria. Researchers found a prevalence of genetic fitness in the population of Sardinians. Selection pressure made them highly effective at defeating malaria. The phenomenon was so finely tuned that people in coastal areas had this fitness and people who had long lived a few miles away in the highlands (where there was no malaria) did not. But Sardinia, like many countries, wiped out malaria in the twentieth century, and then those hypertuned, aggressive immune systems went looking for a new enemy, like an overmuscled bully stewing for a fight. As is often the case, the new target was the body itself. Sardinia today has epidemic levels of the autoimmune disease multiple sclerosis. This is the very pathway that shows up in all the other autoimmune diseases that plague us today in ever-increasing numbers.
We have approached this whole topic as a separate front in the advance of diseases of civilization, but there are in fact interesting connections between the first and second waves, some cross talk between food and immune response. Know that this is not simply a matter of an oddball infectious microbe that we happen to encounter. Microbes are not at all incidental to our lives, an idea that we hope will give you a new way of thinking about yourself as not just yourself. The thing is, you have more microbes, mostly bacteria, inside of you right now than there are humans on earth. Bacterial cells inside you outnumber your own cells, and the genetic code of the raw information of the microbes that you contain dwarfs your own genetic code. Yours is a thumb drive to their terabytes of hard drive.
Do you think nature would use all of that information for nothing, or that those uses have nothing to do with your health and well-being?
Consider raw energetics, for instance. Remember: we humans need all the help we can get to boost our streamlined digestive system, and clearly we use microbes for this very reason. An argument we will make later on is that the often-cited dictum of traditional nutrition that says a calorie is a calorie is just plain wrong. Some research has shown that the calorie content made available to your body is, in fact, to some degree dependent on the type of bacteria in your digestive system, a population that varies wildly from person to person. But in a marvelous display of symbiosis, what happens typically is the bacteria in your digestive system live off your food—that is, they take the energy they need, and at the same time make some energy more available to you, increasing energy content by, on average, 10 percent. There is a species of bacteria found in obese mice that, wh
en transplanted into other mice, makes them obese. Same diet. New bacteria, and they become obese. There is some evidence that certain bacteria give us vitamins we wouldn’t normally extract from food. But even “good” bacteria can go bad in interesting ways.
For instance, in one experiment, researchers fed normally lean people a diet of junk food and noted a flourishing of a species of bacteria that caused the subjects to harvest even more calories from the junk food and in turn grow more obese. But because these are bacteria, they are of interest to our immune systems, and immune systems sometimes respond to invasions with inflammation. We will have a lot to say about inflammation as this book goes on, but know that many researchers now worry far more about inflammation than they do about cholesterol in the origins of heart disease, not to mention cancers. In the junk food experiment, those flourishing junk food bacteria produced a marked increase in both inflammation and insulin resistance, which is the indicator at the dead center of diseases of civilization.
Yet all of this merely scratches the surface of a largely unexplored universe. Our bodies contain thousands of species of bacteria, each with the potential to affect our well-being in direct ways; we know almost nothing about them, and yet we, for generations, have not hesitated to introduce tidal waves of upheaval into our internal biomes with routine doses of antibiotics.
Further, once this complex system has been so disturbed—and there is no doubt it has been in each of us—we still have not the foggiest clue as to how to put it back together.
A generation ago, scientists working in another field (literally a field) faced a similar problem, and it offers an informative analogy, perhaps even an exact parallel. The issue was simple enough that a few conservation biologists hatched plans to conduct what was then called restoration ecology: the idea of restoring intact ecosystems. That’s the first step in connecting you to this analogy. You are not an individual so much as you are an ecosystem. Your health and well-being depend on the health of that ecosystem. You confront the exact same problem of restoration ecology in your internal biome.
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